This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of computer systems, it may be desirable for information to be transferred from a system memory associated with one computer system to a system memory associated with another computer system. The information may be transmitted by upper layer protocols (ULPs), which may be referred to as processes, through a network that connects the computer systems. These ULPs may utilize other protocols to perform the actual data exchange between the computer systems. In addition, the ULPs may utilize other protocols to manage the flow of data between the computer systems.
Some ULPs may operate in this environment without problems because ULPs precisely estimate the memory demands to satisfy the data transfer needs or control the amount of data to not overrun available memory at the receiver. These ULPs implement precise flow control for messages that are communicated with other ULPs. As such, when communicating with peer ULPs via other protocols to receive the inbound data transfers, a ULP may guarantee receive buffer availability because the memory demands are known and deterministic. In such an environment, if a data packet is received and no receive buffer is available, the ULP and protocols utilized by ULP for the data transfer may assume that an error has occurred. The ULP or protocols may then terminate the connection between the ULPs, which may result in a loss of data or commands that are being exchanged.
However, for other ULPs and protocols with imprecise flow control, the termination of the connection between the ULPs, is not an acceptable approach. For instance, if the ULP utilizes a protocol to manage the data transfer, such as an internet small computer systems interface (“iSCSI”) protocol, it may have limited flow control capabilities. The protocol may not manage various types of commands because it has a limited flow control. As a result, other protocols assisting the iSCSI protocol in the data transfer, such as a datamover protocol, may be utilized to enforce stricter forms of send message flow control to deterministically manage the flow control within the data exchange. The stricter send message flow control may increase the complexity of the system, and lead to drawbacks in scalability.